Can anybody explain this one to me. Just installed XAMPP for Windows 5.6.12 on my pc and I was putting a table together with only three columns which were "cid"with auto increment & integer and length of 5, username with varchar at 55, and date with timestamp. When I went to save the table it appeared in a popup tooltip.

That is what I thought at first but for some reason I was suspicious of the fact that the column cid was given a primary key and auto increment. I started over and created the table without those attributes and it came together as planned, after which I assigned the primary key and auto-increment. I'm wondering what kind of problems it will cause in the future.